Hand screw clamp

Abstract: A hand screw clamp (10) includes first and second jaws (12,14) and a pair of threaded rods (30), each having a handle (32) for manual rotation. Two first couplers (44) are mounted to the first jaw (12) and coupled to the threaded rods (30), and two releasable couplers (50) are mounted to the second jaw (14) and coupled to the threaded rods (30). The releasable couplers (50) each include a threaded portion (52) engageable with the threaded rods (30) and a slidable portion (54) sized to accommodate sliding movement of the threaded rods (30). A push plate (60) is movably mounted to the second jaw (14) and engaged with both of the releasable couplers (50). This push plate (60) is movable between a first position, in which both of the threaded portions (52) are engaged with the rods (30) and manual rotation of the handles (32) moves the second jaw (14) along the threaded rods (30), and a second position, in which both of the threaded portions (52) are disengaged from the threaded rods (30) and the threaded rods (30) are free to slide past the slidable portions (54) without rotation of the threaded rods (30).

Description: The invention relates to a hand-screw clamp according to the preamble part of claim 1. Hand-screw clamps have long been a preferred clamp for cabinet makers and other woodworkers. Conventionally, such clamps include two jaws which are interconnected by two threaded rods. Threaded couplers are provided on each of the rods, rotatably mounted in each of the jaws. Typically, each threaded rod has two threaded portions which are threaded in opposite senses, and the threaded rods can be manually rotated to adjust the tilt angle between the first and second jaws, and to clamp a workpiece between the jaws. Conventional hand-screw clamps suffer from the disadvantage that they require extensive rotation of the threaded rods to move the jaws from a fully-opened to a fully-closed position. A hand-screw clamp as known from US-A-368 278 is equipped with an actuation element for releasing both threaded couplers from their respective threaded engagements with the threaded rods. Upon disengagement of the couplers, the second jaw can be moved along the threaded rods without rotating the threaded rods. After releasing the actuation elements, springs return the couplers into their threaded engagement with the threaded rods. The actuation element is movable parallel to the axis of both threaded rods and in the plane of the axis. Said known hand-screw clamp represents relevant prior art mentioned in the preamble part of Claim 1. A hand-screw clamp as known from US-A-3 220 721, Fig. 2, contains a slide in the second jaw, constituting both threaded couplers which are adapted to couple the second jaw with both threaded rods in an extended position of the slide. The slide is movable within the plane of the axis of both threaded rods, and perpendicularly with respect to said axis within the second jaw. A head of said slide protrudes from one end of the second jaw. The engagement position of the slide is made by a spring supported in the second jaw. Upon movement of the slide into a retracted position, the threaded engagement between the slide and both threaded rods is released for free sliding movement of the second jaw along both threaded rods. GB-A-563 870 discloses a manually operable clamp including releasable couplers mounted to a fast-adjusting jaw for cooperation with the rods. Both couplers are connected via a transverse plate which is movable along a direction substantially transverse to a plane passing through both rods. Along the sides of each rod facing one of the couplers, a plurality of shallow lateral grooves is provided allowing a positive engagement of the associated coupler in its engagement position. Said coupler includes a circumferential notch which can be aligned with the associated rod in the release position of said coupler in order to allow a quick sliding adjustment of the jaw comprising said couplers. Both couplers are firmly secured to said transverse plate. Compression springs provided between said jaw and said transverse plate maintain said couplers via said transverse plate in their respective engagement positions. In order to adjust the clamp by moving one jaw, either over a large scale or from one groove to the next following groove, said transverse plate has to be operated accordingly. It is a task of the invention to improve a hand-screw clamp as disclosed for easy operation by the user. This is achieved by a hand-screw clamp according to claim 1. In the engaged position of the actuating element, both threaded portions of the couplers are engaged with the respective threaded rods. Manual rotation of the handles moves the second jaw along the threaded rods. In the disengaged position of said actuating element, both of the threaded portions of the couplers are disengaged from the threaded rods. Then, large scale adjustment of the second jaw can easily be made. When a user releases the push plate and rotates the threaded rods, the hand-screw clamp operates like a conventional hand-screw clamp. Selective rotation of the threaded rods allows a clamping force to be developed between the jaws while also allowing the tilt angle between the jaws to be adjusted. When a user decides to open or close the jaws by a large amount, he simply depresses the push plate perpendicularly to the plane of the threaded rods into the release position. Then, the releasable couplers are no longer threadedly engaged with the threaded rods, and the threaded rods are free to slide without rotation. The flanges of the push plate are engaged with the releasable couplers, and these flanges operate as means for causing the releasable couplers to move in response to the movement of the push plate. As both couplers are received in their respective cylindrical recesses in a movable manner, and are connected via a flange/groove-connection with the push plate, their threaded portions can threadably engage the threaded rods in a reliable way when the threaded rods are rotated to apply clamping pressure between the jaws. Preferred embodiments are contained in the dependent claims. An embodiment of the invention is shown in the drawings, in which: Figure 1 is a front view of a hand screw clamp which incorporates a preferred embodiment of this invention, showing the jaws clamping a workpiece with parallel sides. Figure 2 is a sectional view taken along line 2-2 of Fig. 1. Figure 3 is a rear view of the clamp of Fig. 1, showing the jaws clamping a workpiece with non-parallel sides. Figure 4 is a partial sectional view taken along line 4-4 of Fig. 2. Figure 5 is a perspective view of one of the first couplers of the clamp of Fig. 1. Figure 6 is a perspective view of one of the releasable couplers of the clamp of Fig. 1. Figure 7 is a sectional view taken along line 7-7 of Fig. 6. Figure 8 is a sectional view taken along line 8-8 of Fig. 1 showing the releasable couplers engaged with the two threaded rods. Figure 9 is a sectional view corresponding to Fig. 8 showing the releasable couplers disengaged from the threaded rods. DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS Turning now to the drawings, Figs. 1-3 show a hand screw clamp 10 which incorporates a presently preferred embodiment of this invention. The hand screw clamp 10 includes first and second jaws 12, 14, each provided with an elastomeric clamping pad 16. The jaw 14 defines a finger depression 18 on one side (Fig. 3), and a thumb depression 20 and a hand depression 22 on the opposed side (Fig. 1). A user can readily grasp the jaw 14 by placing his fingers in the finger depression 18, his thumb in the thumb depression 20, and the heel of his hand in the hand depression 22. In this embodiment the jaws 12, 14 are molded of a synthetic material such as glass reinforced nylon, and the jaws 12, 14 define strengthening cross webs 24. Of course, in alternative embodiments the jaws 12, 14 can be formed of wood or other suitable materials. The pads 16 may be formed of a material such as Santoprene, a trademark of Monsanto. The jaws 12, 14 each define two cylindrical recesses 26 which intersect slots 28 (Figs. 1 and 4). The slots 28 are generally hourglass in shape for reasons explained below. As shown in Fig. 1, the clamp 10 includes a pair of threaded rods 30, each having a handle 32 affixed to one end. Each of the threaded rods 30 defines a threaded portion 38 which extends along almost the entire length of the rod 30, threaded in a single sense. One of the threaded rods 30 defines a stop ring 42 at its free end. This threaded rod 30 defines an annular groove 34 situated between two flanges 36 at the end adjacent the respective handle 32 (Fig. 4). The other of the threaded rods 30 defines a similar groove 34 and flanges 36 at the free end of the threaded rod 30, opposite the respective handle 32 (Fig. 4). In this embodiment, the handles are formed of a synthetic material such as polypropylene or another suitable material such as wood. A pair of first couplers 44 are positioned in the cylindrical recesses 26 of the first jaw 12. These first couplers 44 each define a slot 46 sized to receive a respective one of the threaded rods 30 with the first coupler 44 fitting into the groove 34, and the flanges 36 bearing on the first coupler 44 to prevent axial movement between the first couplers 44 and the threaded rods 30 (Fig. 5). The first couplers 44 are preferably mounted for rotation in the first jaw 12 while being restrained against axial movement out of the cylindrical recesses 26. A pair of releasable couplers 50 are rotatably mounted in the cylindrical recesses 26 of the second jaw 14. As shown in Figs. 6 and 7, each of the these releasable couplers 50 includes a threaded portion 52 and an enlarged slidable portion 54. In this embodiment, the threaded portions 52 engage between a quarter and a third of the circumference of the threaded rod 30 and can therefore be described as quarter nuts. Each of the releasable couplers 50 defines an outer flange 56 and an adjacent groove 58. As shown in Figs. 8 and 9, a push plate 60 defines a pair of openings and associated flanges 62 which fit into the grooves 58 of the releasable couplers 50. Compression coil springs 64 are mounted in recesses in the second jaw 14 to bear on the releasable couplers 50 and to resiliently bias the releasable couplers 50 and the push plate 60 to the extended or engaged position shown in Fig. 8. Manual pressure on the push plate 60 (exerted for example by a user closing his hand with his fingers in the finger depression and his thumb and hand in the thumb and hand depressions) overcomes this resilient biasing force to move the push plate 60 and the releasable couplers 50 to the depressed or disengaged position shown in Fig. 9. In this embodiment, the couplers 44, 50 and the rods 30 are formed of heat treated carbon steel and the push plate is formed of a suitable synthetic material such as polypropylene. Alternative embodiments can use other materials such as high strength plastics for the couplers 44, 50 and the rods 30. As best shown in Fig. 9, the releasable couplers 50 are oriented with the deeper part of the threaded portions 52 to the outside. This allows the threaded portions 52 to threadedly engage the threaded rods 30 in a reliable way when the threaded rods 30 are rotated to apply clamping pressure between the jaws 12, 14. When a user releases the push plate 60 and rotates the threaded rods 30, the hand screw clamp 10 operates like a conventional hand screw clamp. Selective rotation of the threaded rods 30 allows a clamping force to be developed between the jaws 12, 14, while also allowing the tilt angle between the jaws 12, 14 to be adjusted. The hourglass shape of the slots 28 (Fig. 1) accommodates a range of tilt angles between the jaws 12, 14. In this mode of operation, the push plate 60 and the releasable couplers 50 are in the engaged position shown in Fig. 8, and the threaded portions 52 threadedly engage the threaded rods 30. When a user desires to open or close the gap between the jaws 12, 14 by a larger amount, he simply depresses the push plate 60 to the position shown in Fig. 9. In this position, the releasable couplers 50 are moved such that the threaded portions 52 are no longer threadedly engaged with the threaded rods 30, and the threaded rods 30 are free to slide through the slidable portions 54, without rotation of the threaded rods 30. In this mode of operation, the user can quickly make large scale adjustments to the position of the second jaw 14 with respect to the first jaw 12 by simply sliding the second jaw 14 along the stationary threaded rods 30. When these large scale adjustments are completed, the user simply releases the push plate 60, and the push plate 60 and the releasable couplers 50 are returned to the engaged position of Fig. 8 by the springs 64. Note that the push plate 60 is oriented parallel to a plane passing through the threaded rods 30, and the push plate 60 is therefore easily operated by the user. In the engaged position of Fig. 8, the push plate 60 is farther from the threaded rods 30 than in the disengaged position of Fig. 9. This means that a simple squeezing action of the user can move the push plate 60 and the releasable couplers 50 to the disengaged position, and that the normal position of the push plate 60 and the releasable couplers 50 is the engaged position of Fig. 8. From the foregoing, it will be apparent that the push plate 60 operates as a means for allowing a user to move both of the releasable couplers 50 simultaneously to the disengaged position of Fig. 8 with one hand. This allows convenient, reliable and simple operation of the clamp 10. The flanges 62 of the push plate 60 are engaged with the releasable couplers 50, and these flanges 62 operate as means for causing the releasable couplers 50 to move in response to movement of the push plate 60. An actuating element such as a control button or switch can be provided, and the means for causing the releasable couplers to move in response to movement of this actuating element can include an active control system such as electrically powered solenoids or a spring powered mechanism. Of course, it should be understood that a wide range of changes and modifications can be made to the preferred embodiments described above. For example, the first couplers 44 can be threaded rather than slotted to threadedly engage the threaded rods 30, and the first couplers 44 can be made releasable if desired. In this case the threaded rods can be provided with two threaded regions that are threaded in opposite senses. The releasable couplers 50 can include quarter nuts as shown, or they can alternately be formed of other types of releasing threaded couplers which shift to release the coupler from the threaded rod. The springs 64 can be positioned to operate between the push plate 60 and the jaw 14, and they can be embodied as other types of springs, including torsion springs, extension springs and the like.

Claims: A hand screw clamp (10) comprising first and second jaws (12,14); a pair of threaded rods (30) coupled to the first jaw and each comprising a handle (32) for manual rotation; a pair of releasable couplers (50) mounted to the second jaw (14) and coupled to the threaded rods (30), said releasable couplers (50) each comprising a threaded portion (52) engageable with the respective threaded rod and a slidable portion (54) sized to accommodate sliding movement of the respective threaded rod; an actuating element (60) movably mounted to the second jaw (14) and engaged with both of the releasable couplers (44,50), said actuating element (60) positioned adjacent the second jaw (14) said actuating element (60) movable between an engaged position, in which both of the threaded portions (52) are engaged with the respective threaded rods (30) and manual rotation of the handles (32) moves the second jaw (14) along the threaded rods (30), and a disengaged position, in which both of the threaded portions (52) are disengaged from the respective threaded rods (30) and the threaded rods (30) are free to slide past the slidable portions without rotation of the threaded rods (30), Characterised in that a pair of first couplers (44) is mounted to the first jaw (12) for coupling the first jaw to the threaded rods (30); said actuating element (60) is movable along a direction substantially transverse to a plane passing through the threaded rods (30), said threaded rods (30) passing through openings provided in the releasable couplers (50), the threaded portion (52) and the slidable portion (54) being provided on opposing sides of the peripheral surface of each opening, said releasable couplers (50) being mounted in cylindrical recesses (26) of said second jaw (14) such that they can be rotated about an axis substantially transverse to a plane passing through the threaded rods (30) and can be axially moved in said recesses (26) from an engaged position where said threaded portion (52) engages said respective threaded rod to a second position where the slidable portion (54) allows sliding movement of the respective threaded rod, that each releasable coupler (50) defines an outer flange (56) and a groove (58) adjacent to said flange (56), that said actuation element (60) is a push plate defining a pair of openings and associated flanges (62), and that the outer flanges (56) of both releasable couplers (50) are inserted into said openings of said push plate such that flanges (62) associated with said openings fit into said groove (58) adjacent said flanges (56) of said releasable couplers and rotatably mount said releasable couplers (50) on said push plate. Hand-screw clamp of claim 1 characterized in that in the recesses (26) of said second jaw (14), compression coil springs (64) are provided, bearing on the couplers (50) to resiliently bias the releasable couplers (50) and the push plate along said direction substantially transverse to said plane passing through the threaded rods to said engaged position. Hand-screw clamp of claim 1 characterized in that each of the releasable couplers (50) comprises a quarter nut. Hand-screw clamp of claim 1 characterized in that each of the first couplers (54) comprises a slot (46) that rotatably receives and axially holds the respective threaded rod (30) in the first jaw (12).

Inventors: BECKMANN TOBY J, SORENSE JOSEPH A, BECKMANN,TOBY J., SORENSE, JOSEPH A.
Applicants: PETERSEN MFG, PETERSEN MANUFACTURING CO., INC.
Application year: 1994
Main classification: B25B5
IPC codes: B25B5, F16B2